Hand trucks have been adapted in various ways to facilitate the carrying of loads. U.S. patent application Ser. No. 698,110, filed Feb. 4, 1985, now U.S. Pat. No. 4,637,769, by the same party as this patent is assigned to, discloses a hand truck for carrying heavy objects. The hand truck includes a frame mounted on a wheel assembly. The lower portion of the frame serves as a bed on which objects can be supported. At the base of the frame is a heel, or a plurality of projections that extend out above the frame bed. A hook, hingedly secured to the frame above the frame bed, has a grip point that is oriented toward the frame bed. When an object is placed on the truck, gravity forces the hook downward so that the object is seized by the grip point and secured to the frame bed. Stabilizing wedges on the frame urge the object toward the grip point to insure that the object continually remains seized by the grip point. Thus, the object will remain secured to the hand truck while it is being transported thereon.
Current hand trucks, though useful, can transport objects only from one ground or floor location to another. They cannot be used to load or unload objects that are located a few feet off the ground. Thus, when it is necessary to transport an object to or from an elevated area, such as a work station, or a storage location, it is usually necessary to manually lower or raise the object to or from the ground. Often the objects to be transported are too heavy for one person to raise or lower. Also, some objects, such as large logs and stones, are without grasping points and are rather bulky, and thus are difficult to hold onto. This adds to the difficulty of lifting and lowering these objects.
Furthermore, with many hand trucks, the strength of the seizing or grasping arm is gravity dependent. In some situations, such as transporting objects outdoors or over uneven terrain, the force exerted by the arm may be insufficient to securely hold the object to the hand truck in the face of the jarring motion encountered in moving over such terrain. The operator may have to use considerable care in transporting the objects, or the object may work itself free of the truck. If the object does come free of the hand truck, the operator must then resecure it to the truck. Moreover, in some situations the terrain may be such that the seizing arm cannot secure the object in place on the truck even with great care by the operator. In such instances it may be impossible to use the hand truck and the objects have to be transported manually.
A need therefore exists for a new carrying apparatus for transporting heavy objects. The apparatus should be able to transport objects and be able to elevate them above or lower them to the ground. The new apparatus should also have a means to keep the objects firmly secured to the truck while being transported, regardless of the terrain the apparatus travels. In addition the apparatus should be relatively simple to operate and not require the operator to exert significant physical effort.